It turns out he was unarmed and was there to "test" school security.
He has since been arrested.
From an article:
Officials say Ronald Miller was unarmed Wednesday when he told a school greeter outside Celina Elementary School that he had a gun, according to NBCDFW.com. The town of Celina is just north of Dallas.
The greeter froze in panic when Miller said he was a gunman and his target was inside, Celina Independent School District Superintendent Donny O’Dell told NBCDFW.com. Miller was then able to walk into the school and entered the office.
“He told them that he is a shooter and ‘you’re dead, and you’re dead,’” O’Dell told NBCDFW.com. Never showing a weapon, Miller then reportedly revealed his stunt was a test of school safety and he wanted to talk to the principal.
School staffers knew Miller, who was a father of a student, and police were not called until he left the school. He was arrested Wednesday evening and is being held in lieu of $75,000 bail.